Tensioning apparatus

ABSTRACT

Tensioning apparatus for maintaining one or more strands under substantially constant tension during pay out includes a let-off stand for each spool of strand material and a pivotally mounted dancer bar having a dancer roll thereon engaging the strand material. A tension load is applied to the dancer bar which controls the amount of braking force applied to each spool. Should the pulling force on the strand material increase, the dancer bar automatically moves to a position causing a reduction in the braking force, whereas should there be a reduction in the pulling force, the dancer bar automatically moves to a position causing an increase in the braking force thus to maintain a substantially constant tension on the strand material. Where plural strands are being payed out at the same time, the tension in all of the strands may be controlled as a group by providing a single load tensioning device for all of the dancer bars in the group.

United States Patent 1191 Alexeff 1 [54] TENSIONING APPARATUS [75] Inventor: Alexander V. Alexeft, Cleveland,

Ohio

[73] Assignee: Alexeff-Snyder Cleveland, Ohio 22 Flledi Feb. 1,1971

21 Appl.No.: 111,2 0

Enterprises, Inc.,

[ May 8, 1973 FOREIGN PATENTS OR APPLICATIONS 230,593 10/1960 Australia ..242/l56.2 1,369,072 6/1964 France ..242/l56.2

Primary ExaminerStanley N. Gilreath Attorney-Oberlin, Maky, Donneily & Renner [57] ABSTRACT Tensioning apparatus for maintaining one or more strands under substantially constant tension during pay out includes a let-off stand for each spool of strand material and a pivotally mounted dancer bar having a dancer roll thereon engaging the strand material. A tension load is applied to the dancer bar which controls the amount of braking force applied to each spool. Should the pulling force on the strand material increase, the dancer bar automatically moves to a position causing a reduction in the braking force, whereas should there be a reduction in the pulling force, the dancer bar automatically moves to a position causing an increase in the braking force thus to maintain a substantially constant tension on the strand material. Where plural strands are being payed out at 11 Claims, 9 Drawing Figures PATENTEDPW 8W 3.731.889

SHEET a: 0F 4 INVENTOR. AU. EXA/VDEF? V. ALEXEFF PATENIEW 3.731.889

sum 3 [1F 4 INVENTOR.

ALEXANDER V. AL [XE FF A TTORNEYS PATENTED 81915 3,731.889

SHEET t {1F INVENTOR. ALEXANDER l ALEXEFF A TTORNEYS TENSIONING APPARATUS BACKGROUND OF THE INVENTION This invention relates generally as indicated to a tensioning apparatus, particularly for use in maintaining a substantially constant tension during pay out of fabric or strand-like material from one or more material letoff stands.

Constant tensioning devices have of course long been used in the textile industry to maintain uniform tension in the thousands of strands which go into the weaving of a single piece of cloth. If a constant tension were not maintained, the cloth would not be uniformly woven. As the strands are withdrawn from spools mounted on let-off stands in a creel room, small tensioning devices provide the desired tension in each strand. Usually, the tensioning devices are of the friction type and include a set of horizontally mounted friction wheels over which the strands pass.

Although such tensioning devices have proven to be quite satisfactory in the textile industry, they are not Suitable for obtaining the higher tensions required in other industries, including the tire industry when strands of flexible wire and the like are used in the manufacture of certain types of tires. At present the tension is regulated in the tire industry with the use of magnetic brakes controlled by otentiometers, or air brakes or electronic dancer units. Regardless of the type of tensioning device used, they all require complicated wiring or piping configurations, making them quite costly and complex. In addition, they have the further objection that when they are arranged in groups, individual control of each tensioning device is completely lost, making it impossible to compensate for variations in tension of the strands caused by differences in spool diameters and the like. Heretofore, there was no way to control automatically each individual spool tension while changing the tension of the entire group; the tension for each let-off stand had to be set manually to correspond with the group tension.

SUMMARY OF THE INVENTION With the foregoing in mind, it is a principal object of this invention toprovide a tensioning apparatus of simplified construction wherein individual tension control of a plurality of let-off stands is superimposed by group control.

Still another object is to provide such a tensioning apparatus which may include any number of let-off stands for controlling the tension of any number of strands as a group with each individual let-off stand automatically maintaining the desired group tension for each strand.

Another object is to provide such a tensioning apparatus which is simple to operate and does not require separate electrical or pneumatic controls for each individual unit.

Another object is to provide such a tensioning apparatus with the safety feature of automatically stopping the spool from rotating in the event of breakage of the strand material.

Briefly, the tensioning apparatus of the subject invention consists of one or'more let-off strands, one for each spool, and a pivotally mounted dancer bar for each let-oft stand supporting a dancer roll or pulley engaged by the strand material. A tension force is applied to each dancer bar to control the braking force applied to the spool. Should the pulling force on the strand material increase, the danger bar will automatically pivot in a direction causing a reduction in the braking force, whereas should the pulling force on the strand material decrease, the dancer bar will automatically pivot in the reverse direction causing an increase in the braking force thus to maintain the tension in the strand material substantially constant. Where plural let-off stands are provided, the tension in each strand may be controlled as a group by providing a single load tension device for all of the dancer bars, preferably with a yieldable connection between the individual dancer bars and the load tension device to permit variations in the movement of each dancer bar for maintaining the desired tension in each strand.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, .the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS In the annexed drawings:

FIG. 1 is a schematic side elevation view of one form of tensioning apparatus constructed in accordance with this invention;

FIG. 2 is a schematic end elevation view of the tensioning apparatus of FIG. 1 as seen from the plane of the line 2--2 at the rightend of FIG. 1;

FIG. 3 is a schematic side elevation view of another form of tensioning apparatus in accordance with this invention;

FIG. 4 is a schematic fragmentary end elevation view of a modified form of tensioning apparatus in which a sliding pulley is used in place of the dancer roll of the previous embodiments;

FIG. 5 is a schematic side elevation view of yet another form of tensioning apparatus in accordance with this invention utilizing a plurality of let-off stands similar to those shown in FIGS. 1 through 3 connected together for operation as a unit or group;

FIG. 6 is a fragmentary side elevation view of the tensioning apparatus of FIG. 5 except that the operation of the load tensioning device has been reversed to permit free rotation of the spools on the let-off stands;

FIG. 7 is a schematic side elevation view of still another form of tensioning apparatus in which plural groups of let-off stands are connected together for operation as a single unit;

FIG. 8 is a schematic side elevation view of still another form 'of tensioning apparatus in accordance with this invention; and

FIG. 9 is an end elevation view of the tensioning apparatus of FIG. 8 as seen from the plane of the line 9- -9 at the right end of FIG. 8.

DESCRIPTION or THE PREFERRED EMBODIMENTS Referring now in detail to the drawings, and initially to FIGS. 1 and 2 thereof, there is shown one form of tensioning apparatus 1 in accordance with this invention including a let-off stand 2 on which is rotatably mounted a spool 3 of strand-like material such as wire or cord as shown. Although only one such let-off stand 2 is shown, it will be appreciated that any number of let-off stands may be provided, one being required for each spool from which material is to be payed out. Each let-off stand 2 desirably includes a main support frame 4 having a shaft 5 journaled thereto at one end in cantilevered fashion leaving the other end free for ready insertion of the spool onto the shaft. Fixed to the inner end of the shaft 5 is a hub 6 having a pin 7 extending into an opening in the spool providing a driving connection between the shaft and spool.

Also mounted on the inner end of the shaft 5 is a brake drum 8 with brake band 9 wrapped therearound. One end of the brake band 9 is fixed to the main support frame 4 and the other end is connected to one or more dancer bars 10 pivotally mounted at one end to the main support frame 4 or other fixed support below the shaft 5, whereby lowering and raising of the dancer bars will cause a corresponding increase and decrease in the frictional drag of the brake band 9 against the brake drum 8 thus to control the amount of tension in the strand S during pay out. The brake band 9 may be connected to the dancer bars 10 by a suitable spring connection 12 to soften the 'load applied to the brake drum 8 by the brake band 9 during lowering of the dancer bars. In the form illustrated the spring connection 12 consists of a rod 13 extending through an opening 14 in a mounting bracket 15 attached to the inner dancer bar 10, and a spring 16 interposed between the bracket 15 and a nut 17 on the free end of the rod which may be tightened or loosened as desired to vary the tension of the spring.

Also carried by the dancer bars 10 outwardly of the brake band connectionlZ is a shaft 18 having a dancer roll 19 journaled thereon in line with the spool 3 on the let-off stand 2 in radial spaced relation therefrom. Alternatively, a pulley 20 may be slidably received on the shaft 18 in place of the dancer roll 19 as shown in FIG. 4. In any event, the strand material S is payed out from the top of the spool 3 and wrapped around the underneath side of the dancer roll 19 or pulley 20 as shown in FIGS. 1, 2 and 4. From the dancer roll 19 or pulley 20 the strand material S may be wrapped around a fixed idler roll 21 vertically spaced above the dancer roll and then fed to suitable processing equipment, for example, a calender where the strand material is pressed into rubber strip material.

To control the tension in the strand material S as it is pulled from the let-off stand 2, a load is applied to the dancer bars 10 urging the dancer bars downwardly about the pivot point 22 with a predetermined force sufficient to counterbalance the braking force and maintain sufficient frictional drag by the brake band 9 against the brake drum 9 to maintain a substantially constant tension in the strand during pay out despite variations in the rate of withdrawal of the strand from the spool 3 and variations in diameter of the spool during withdrawal of the strand material.

In the tensioning apparatus 1 shown in the FIGS. 1 and 2 embodiment, a weight 23 is provided on the outer end of the dancer bars 10 which may be varied as desired to vary the tension in the strand, and the weight 23 may also be slidably mounted on the dancer bars 10 as shown to vary its effective weight by varying the distance between the dancer bar pivot 22 and the weight 23 as measured by a scale 24 on the outer end of the outer dancer bar. Alternatively, a spring 25 may be used to apply a load to the dancer bars 10 as shown in FIG. 3 wherein one end of the spring 25 is shown attached to the outer dancer bar and the other end of the spring is attached to a fixed support 26. Utilizing a spring 25 for applying the load has the advantage that it will act as a shock absorber during movement of the dancer bars thus eliminating any possibility of oscillation of the dancer bars. The spring may also be made adjustable to vary the tension in the spring for varying the load applied to the dancer bars and thus varying the tension in the strand as desired. The tensioning apparatus l of the FIG. 3 embodiment is otherwise substantially identical to the tensioning apparatus 1 previously described, and accordingly the same reference numerals followed by a prime symbol are used to designate like parts.

With a particular load applied to the dancer bars 10, the brake band 9 is urged against the brake drum 8 with a predetermined force thus to provide a predetermined resistance to turning of the spool 3 during removal of strand material therefrom which maintains a substantially constant tension in the strand material. The amount of tension in the strand material will remain substantially constant despite variations in the pulling force applied to the strand material and variations in the diameter of the spool during pay out. Should the pulling force on the strand material decrease, the applied load on the dancer bars 10 will cause the dancer bars to move downwardly increasing the braking force on the brake drum 8 thus to maintain the tension in the strand material substantially constant. Converselyf should the pulling force on the strand material increase, the dancer bars 10 will be caused to lift up reducing the braking force on the brake drum 8 to maintain the tension in the strand material substantially constant. Moreover, as the diameter of the spool 3 decreases during pay out of the strand material, the amount of braking force needed to maintain a substantially constant tension in the strand material is reduced by upward movement of the dancer bars.

From the foregoing, it will be seen that the tensioning apparatus previously described makes use of a mechanical brake which when adjusted automatically maintains the required tension in the strand material without the need for the complicated control systems of the usual magnetic and pneumatic functioning devices. Such tensioning apparatus also readily lends itself to group control as by connecting the dancer bars 10 of a plurality of let-off stands 2 to a common load applying mechanism. In FIG. 5 there are shown four such let-off stands 2 with dancer bars 10 all connected to a common load applying member 30 which may consist of a vertically movable beam 31 having a rod 32 on the upper end slidably received in a fixed guide 33 and having an actuator 34 connected to the lower end which in this case is a diaphragm type air motor. By adjusting a pressure gauge 35 which supplies air pressure to the air motor 34 through a needle valve 36, all of the strands S may be maintained under any desired tension,

as for example, from 1 pound to 10 pounds tension on each strand. The dancer bars 10 of each let-off stand 2 are desirably connected to the common load-applying member 31 through separate spring members 37 which automatically maintain the required tension in the strand material from each let-off stand independently of the others to avoid variations in tension from one letoff stand to another due to variations in spool diameters and pulling forces on the various strands andthe like.

While only four such let-off stands 2 are shown grouped together in FIG. 5, it will be apparent that any desired number of let-off stands may be connected to the same load applying member 31, and any number of such groups of let-off stands 2 may also be combined into still another single group as by connecting the load applying members 31 of any number of groups to a further common load applying member 38 which may be raised and lowered by one or more air motors 34 connected thereto at spaced intervals along its length as schematically shown in FIG. 7. The air motors 34 applya transverse load to the load applying member 33 which in turn applies an axial load to the load applying members 31. Ordinarily, the same pressure is supplied to all of the air motors 34 to obtain uniform tension in all of the strands S, but it will be apparent that different pressures may be supplied to different air motors for obtaining different tensions in different groups of letoff stands as desired.

Another advantage in using the tensioning apparatus of the subject invention is that if the strand material from any let-off stands should break, the spool associated with that let-off stand will immediately stop since the pulling force on the broken strand drops to zero and the applied braking force increases. Moreover, if desired the spools 3 on any of the let-off stands 2 may be made freely rotatable simply by reversing the direction of the applied load by the air motor 34 until the frictional force of the brake bands 9 on the brake drums 8 is reduced to zero as schematically illustrated in FIG. 6.

in FIGS. 8 and 9 there is shown a modified form of tensioningapparatus 40 in accordance with this invention which also includes a pair of pivotally mounted dancer bars 41 and dancer roll 42 supported thereby for engagement by the strand material S during pay out. The spool 3 is mounted for rotation with ashaft 33 whose ends are received in a pair of rotatable chuck elements 44 which comprise the let-ofi stand 45. However, instead of controlling the amount of tension in the strand material using a mechanical brake, an air brake 46 is provided on one of the rotatable elements 44. Air pressure to the air brake 46 is controlled by a pressure control valve 47 which is responsive to the movements of the dancer bars 41 to vary the air pressure to the air brake 46 as required to maintain a substantially constant tension in the strand material. The pressure control valve 47 has a pivotally mounted control handle 48 connected to the dancer bars 41 for pivotal movement during raising and lowering of the dancer bars. Although a rigid link may be used to provide the desired connection therebetween, it is preferred to use a relatively strong spring 49 as shown to protect the control valve 47 from being damaged in the event that the dancer bars should be raised more than the maximum strolre of the control handle 48. A second weaker spring 50 is also desirably used to connect the control handle 48 to the let-off stand 45 in opposition to the stronger spring 49 to insure positive control. One or more cylinders 51 are also desirably used to preload the dancer bars 41 and to dampen the movements of the dancer bars during operation. In FIGS. 8 and 9 two such cylinders 51 are shown each having one end connected to one of the dancer bars 41 and the other end connected to the base of the let-off stand 45.

In operation, the position of the control handle 48 as determined by the position of the dancer bars 41 controls the amount of air pressure: supplied to the air brake 46. If the pulling force on the strand material is increased, the dancer bars 41 are lifted upwardly thus to cause a slight upward movement of the control handle 48, which reduces the amount: of pressure supplied to the air brake 36 to maintain a substantially constant tension in the strand material. A reduction in the pulling force on the strand material has the reverse effect, whereby variations in the pulling force on the strand material will have little or no effect on the tension. Nor will a reduction in the diameter of the spool 3 during pay out affect the tension of the strand material, since any tendency to change the tension is automatically compensated for by movements of the dancer rolls and control handle connected thereto. Thus, in effect the air cylinders 51 set the material tension and the air brake 46 maintains such tension substantially constant.

From the foregoing, it will now be apparent that the various tensioning apparatus disclosed herein are of a relatively simple design and allow a substantially constant tension to be maintained in strand and other material during pay out without the need for complicated valving or control systems. Any number of letoff stands may be controlled by the tensioning apparatus for control as a unit without sacrifice of individual adjustment of each let-off stand. When thus grouped, the tension forces in the entire system may be maintained within a small fraction of a pound, and variations in the tension may also readily be made as desired.

I claim:

ll. Tensioning apparatus comprising a plurality of letoff stands, each of said letoff stands including a rotatable shaft, means for mounting a spool of strand material on said shaft for rotation therewith, brake means for applying a braking force to said rotatable shaft to tension the strand material during pay out from said spool, roll means engageable by the strand material and movable toward and away from said spool with increasing and decreasing tension on the strand material, means responsive to such movement of said roll means to vary the amount of braking force applied to said rotatable shaft by said brake means to maintain a sub stantially constant tension on the strand material dur ing pay out, and common load applying means for simultaneously applying a load to a plurality of said roll means for controlling the movements of said plurality of roll means as a group urgingsaid roll means away from their respective spools with a predetermined force which determines the magnitude of the tension maintained on the strand materials during pay out.

2. The tensioning apparatus of claim 1 wherein there is a spring connection between said load applying means and each of said roll means to maintain the desired tension in each strand independently of the others.

3. The tensioning apparatus of claim 1 wherein said load applying means comprises a common load applying member to which all of said roll means are connected.

4. The tensioning apparatus of claim 3 wherein there is a spring connection between said common load applying member and each of said roll means to maintain the desired tension in each strand independently of the others.

5. The tensioning apparatus of claim 3 wherein said load applying means further comprises a fluid cylinder connected to said common load applying member for applying an axial load to said common load applying member.

6. The tensioning apparatus of claim 3 wherein there are plural groups of said let-off stands, said let-off stands of each group being connected to different load applying members, and there is yet another load applying member to which said load applying members for each group are connected for operation of all of the groups as a unit.

7. The tensioning apparatus of claim 6 wherein there are plural fluid cylinders connected to said yet another load applying member at spaced intervals along the length thereof for applying a transverse load to said yet another load applying member which in turn applies an axial load to said load applying members.

8. The tensioning apparatus of claim 1 wherein each of said roll means comprises a pulley, a shaft on which said pulley is slidably received, and a pivotally mounted dancer bar supporting said shaft for pivotal movement toward and away from each of said spools.

9. The tensioning apparatus of claim 1 wherein each of said roll means comprises a dancer roll, and a pivotally mounted dancer bar supporting said dancer roll for pivotal movement toward and away from each of said spools.

10. The tensioning apparatus of claim 9 wherein said brake means comprises a brake drum on each of said rotatable shafts, and said means responsive to such movement of said roll means comprises a brake band engageable with each of said brake drums, each of said brake drums having one end fixed to their respective let-off stands and the other end connected to their respective dancer bars, whereby pivotal movement of said dancer bars toward and away from said spools'will cause a corresponding decrease and increase in the frictional drag of said brake bands against said brake drums.

1 l. The tensioning apparatus of claim 10 further comprising a spring connection between said other end of each of said brake bands and their respective dancer bars to dampen the applied load to said brake drums by said brake bands during movement of said dancer bars away from said spools. 

1. Tensioning apparatus comprising a plurality of let-off stands, each of said let-off stands including a rotatable shaft, means for mounting a spool of strand material on said shaft for rotation therewith, brake means for applying a braking force to said rotatable shaft to tension the strand material during pay out from said spool, roll means engageable by the strand material and movable toward and away from said spool with increasing and decreasing tension on the strand material, means responsive to such movement of said roll means to vary the amount of braking force applied to said rotatable shaft by said brake means to maintain a substantially constant tension on the strand material during pay out, and common load applying means for simultaneously applying a load to a plurality of said roll means for controlling the movements of said plurality of roll means as a group urging said roll means away from their respective spools with a predetermined force which determines the magnitude of the tension maintained on the strand materials during pay out.
 2. The tensioning apparatus of claim 1 wherein there is a spring connection between said load applying means and each of said roll means to maintain the desired tension in each strand independently of the others.
 3. The tensioning apparatus of claim 1 wherein said load applying means comprises a common load applying member to which all of said roll means are connected.
 4. The tensioning apparatus of claim 3 wherein there is a spring connection between said common load applying member and each of said roll means to maintain the desired tension in each strand independently of the others.
 5. The tensioning apparatus of claim 3 wherein said load applying means further comprises a fluid cylinder connected to said common load applying member for applying an axial load to said common load applying member.
 6. The tensioning apparatus of claim 3 wherein there are plural groups of said let-off stands, said let-off stands of each group being connected to different load applying members, and there is yet another load applying member to which said load applying members for each group are connected for operation of all of the groups as a unit.
 7. The tensioning apparatus of claim 6 wherein there are plural fluid cylinders connected to said yet another load applying member at spaced intervals along the length thereof for applying a transverse load to said yet another load applying member which in turn applies an axial load to said load applying members.
 8. The tensioning apparatus of claim 1 wherein each of said roll means comprises a pulley, a shaft on which said pulley is slidably received, and a pivotally mounted dancer bar supporting said shaft for pivotal movement toward and away from each of said spools.
 9. The tensioning apparatus of claim 1 wherein each of said roll means comprises a dancer roll, and a pivotally mounted dancer bar supporting said dancer roll for pivotal movement toward and away from each of said spools.
 10. The tensioning apparatus of claim 9 wherein said brake means comprises a brake drum on each of said rotatable shafts, and said means responsive to such movement of said roll means comprises a brake band engageable with each of said brake drums, each of said brake drums having one end fixed to their respective let-off stands and the other end connected to their respective dancer bars, whereby pivotal movement of said dancer bars toward and away from said spools will cause a corresponding decrease and increase in the frictional drag of said brake bands against said brake drums.
 11. The tensioning apparatus of claim 10 further comprising a spring connection between said other end of each of said brake bands and their respective dancer bars to Dampen the applied load to said brake drums by said brake bands during movement of said dancer bars away from said spools. 